Japanese Patent Application Publication No. 2008-053648 discloses a semiconductor device (a so-called RC-IGBT) including one semiconductor substrate in which a plurality of IGBT regions and a plurality of diode regions are provided. In each of the IGBT regions, a front surface structure of an IGBT is provided on a front surface side of the semiconductor substrate, and a collector region is provided on a back surface side of the semiconductor substrate. In each of the diode regions, a front surface structure of a diode is provided on the front surface side of the semiconductor substrate, and a cathode region is provided on the back surface side of the semiconductor substrate. The IGBT regions and the diode regions are alternately adjacent to each other in a predetermined direction. In a plan view of this semiconductor substrate, each boundary plane between the front surface structure of the IGBT and the front surface structure of the diode is in the same position as each boundary plane between the collector region and the cathode region.